GI, Pharmacology - Lippincott's Questions with correct answers

A 45-year-old male who is obese presents to his primary care physician complaining of postprandial epigastric pain. The pain does not appear after every meal. He has noticed the pain especially after eating spicy foods and oatmeal. He is not currently taking any medications. Which of the following drugs prevents acid secretion by antagonizing a receptor? (A) Aluminum hydroxide (B) Fexofenadine (C) Misoprostol (D) Omeprazole (E) Ranitidine - Answer E: Ranitidine. Multiple factors contribute to acid secretion by parietal cells in gastric mucosa. Gastrin from G cells, histamine from enterochromaffin- like (ECL) cells (acting on H2 receptors), and acetylcho- line from parasympathetic neurons all act directly on parietal cells to induce acid secretion. Prostaglandins from surface mucous cells and somatostatin from D cells directly inhibit acid secretion. Ranitidine is an H2- receptor antagonist, meaning it blocks the proacid effect of endogenous histamine. (A) Aluminum hydroxide does not bind a receptor. It is a base that decreases acid by a simple chemical reaction: H1 1 OH2 → H2O. (B) Fexofenadine is a second-generation H1 antagonist. It would not be expected to significantly bind H2 recep- tors.